Question

在Silverlight中，当您向上或向下按箭头或标签时，当前HIGHLIGHTED（未选中）项目周围会绘制一个小方框。我想找出小方框所在的项目，以便在用户按Tab键时将其设为所选项目。我花了三天时间，也许其他人可以使用它。

       void SelectorRapidAccessKeyBehavior_DropDownOpened(object sender, EventArgs e)
        {
            FindPopup();
        }
        private void FindPopup()
        {
            CleanUpPopupHandler();
            pop = GetPopup(base.AssociatedObject);
            if (pop != null && pop.Child != null)
            {
                pop.Child.KeyDown += AssociatedObject_KeyUp;
                foreach (FrameworkElement c in Finder.FindVisualChildren<FrameworkElement>(pop.Child))
                {
                    c.KeyDown += new KeyEventHandler(c_KeyDown);
                }

            }
        }


        void c_KeyDown(object sender, KeyEventArgs e)
        {
            int t = this.AssociatedObject.TabIndex;
            Border ci = sender as Border;
            if (e.Key == Key.Tab)
            {
                if (ci != null)
                {


//this here is the magic line
                    var v = Finder.FindVisualChildren<FrameworkElement>((DependencyObject)pop.Child).Where(a => a.Opacity > 0 && a.Name == "FocusVisualElement" && a.Visibility == Visibility.Visible);//&& )
                    object o = v.First().DataContext;
                    int i = this.AssociatedObject.Items.IndexOf(o);
                    if (i > -1)
                        this.AssociatedObject.SelectedIndex = i;
                    pop.IsOpen = false;
                    DependencyObject d = Finder.FindParent<FloatableWindow>(this.AssociatedObject);
                    if (d == null)
                        d = Finder.FindParent<Window>(this.AssociatedObject);
                    Control c = Finder.FindVisualChildren<Control>(d).Where(a => a.TabIndex > t).OrderBy(a => a.TabIndex).FirstOrDefault();
                    if (c == null)
                        c = Finder.FindVisualChildren<Control>(d).OrderBy(a => a.TabIndex).FirstOrDefault();
                    if (c != null)
                        c.Focus();
                }
            }
        }

Answer 1

只需将KeyDown事件添加到项目中（可能说起来容易做起来难之）并选择项目，如果Key为Tab，则事件将针对焦点（具有围绕它的框）的事件触发，例如

<ComboBox Loaded="ComboBox_Loaded">
    <ComboBoxItem>1</ComboBoxItem>
    <ComboBoxItem>2</ComboBoxItem>
    <ComboBoxItem>3</ComboBoxItem>
    <ComboBoxItem>4</ComboBoxItem>
    <ComboBoxItem>5</ComboBoxItem>
</ComboBox>

private void ComboBoxItem_KeyDown(object sender, KeyEventArgs e)
{
    if (e.Key == Key.Tab)
    {
        var cbi = sender as ComboBoxItem;
        var cb = cbi.Parent as ComboBox;
        cb.SelectedItem = cbi;
        e.Handled = true;
        cb.IsDropDownOpen = false;
    }
}

private void ComboBox_Loaded(object sender, RoutedEventArgs e)
{
    var cb = sender as ComboBox;
    foreach (var item in cb.Items)
    {
        (item as ComboBoxItem).KeyDown += ComboBoxItem_KeyDown;
    }
}

在WPF中我会知道一些更简洁的方法来附加事件，也许你可以想到一些事情。

Answer 2

  void SelectorRapidAccessKeyBehavior_DropDownOpened(object sender, EventArgs e)
    {
        FindPopup();
    }
    private void FindPopup()
    {
        CleanUpPopupHandler();
        pop = GetPopup(base.AssociatedObject);
        if (pop != null && pop.Child != null)
        {
            pop.Child.KeyDown += AssociatedObject_KeyUp;
            foreach (FrameworkElement c in Finder.FindVisualChildren<FrameworkElement>(pop.Child))
            {
                c.KeyDown += new KeyEventHandler(c_KeyDown);
            }

        }
    }


    void c_KeyDown(object sender, KeyEventArgs e)
    {
        int t = this.AssociatedObject.TabIndex;
        Border ci = sender as Border;
        if (e.Key == Key.Tab)
        {
            if (ci != null)
            {


//this here is the magic line
                var v = Finder.FindVisualChildren<FrameworkElement>((DependencyObject)pop.Child).Where(a => a.Opacity > 0 && a.Name == "FocusVisualElement" && a.Visibility == Visibility.Visible);//&& )
                object o = v.First().DataContext;
                int i = this.AssociatedObject.Items.IndexOf(o);
                if (i > -1)
                    this.AssociatedObject.SelectedIndex = i;
                pop.IsOpen = false;
                DependencyObject d = Finder.FindParent<FloatableWindow>(this.AssociatedObject);
                if (d == null)
                    d = Finder.FindParent<Window>(this.AssociatedObject);
                Control c = Finder.FindVisualChildren<Control>(d).Where(a => a.TabIndex > t).OrderBy(a => a.TabIndex).FirstOrDefault();
                if (c == null)
                    c = Finder.FindVisualChildren<Control>(d).OrderBy(a => a.TabIndex).FirstOrDefault();
                if (c != null)
                    c.Focus();
            }
        }
    }

在Combobox中找到HIGHLIGHTED（未选中）项目

2 个答案: